西亚试剂：多鳍鱼陆上学步

多鳍鱼(多鳍鱼属)是原始辐鳍鱼，见于非洲(有时在家庭鱼缸里也能见到)，它们拥有能够发挥功能的、从鱼鳔演变来的肺和强有力的胸鳍，后者的作用是偶尔上岸时用来支撑身体。

这项研究将“塞内加尔多鳍鱼”(Polypterus senegalus)作为四足动物直接祖先的一个模型，并对这些鱼到陆地上生活时所发生的解剖和行为变化进行量化。

当在陆地上长大时，多鳍鱼会将头抬得高于地面，使前肢接近中线，并且比那些在水下长大、第一次上岸要得到提示才会走路的多鳍鱼滑来滑去的时候要少得多。

这些观察结果再加上骨骼结构和肌肉组织的变化表明，在最早四足动物或者说其直接祖先中所看到的一些姿势变化，也许是对环境的一种反应，并且被发育可塑性吸收了。

原文摘要：

Developmental plasticity and the origin of tetrapods

Emily M. Standen, Trina Y. Du & Hans C. E. Larsson

The origin of tetrapods from their fish antecedents, approximately 400 million years ago, was coupled with the origin of terrestrial locomotion and the evolution of supporting limbs. Polypterus is a member of the basal-most group of ray-finned fish (actinopterygians) and has many plesiomorphic morphologies that are comparable to elpistostegid fishes, which are stem tetrapods.Polypterus therefore serves as an extant analogue of stem tetrapods, allowing us to examine how developmental plasticity affects the ‘terrestrialization’ of fish. We measured the developmental plasticity of anatomical and biomechanical responses in Polypterus reared on land. Here we show the remarkable correspondence between the environmentally induced phenotypes of terrestrializedPolypterus and the ancient anatomical changes in stem tetrapods, and we provide insight into stem tetrapod behavioural evolution. Our results raise the possibility that environmentally induced developmental plasticity facilitated the origin of the terrestrial traits that led to tetrapods.

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